1. Field of the Invention
The present invention relates, in general, to devices and methods for controlling obesity, and, more particularly, a gastric band or gastric band assembly/system, and corresponding methods, configured for self-monitoring and adjustment of the size, i.e., internal diameter, of the gastric band so as to provide ongoing adjustment of stoma size in a patient.
2. Relevant Background
Severe obesity is an increasingly prevalent chronic condition that is difficult for physicians to treat in their patients through diet and exercise alone. Gastrointestinal surgery is used by physicians to treat people who are severely obese and cannot lose weight by traditional means or who suffer from serious obesity-related health problems. Generally, gastrointestinal surgery promotes weight loss by restricting food intake, and more specifically, restrictive operations limit food intake by creating a narrow passage or “stoma” from the upper part of the stomach into the larger lower part, which reduces the amount of food the stomach can hold and slows the passage of food through the stomach. Initially, the stoma was of a fixed size, but physicians have more recently determined that the procedure is more effective if the stoma can be adjusted to alter its size.
One of the more commonly used of these purely restrictive operations for obesity is adjustable gastric banding (AGB). In an exemplary AGB procedure, a hollow band (i.e., a gastric band) made of silicone elastomer is placed around the stomach near its upper end, creating a small pouch and a narrow passage (i.e., a stoma) into the rest of the stomach. The band is then inflated with a saline solution by using a non-coring needle and syringe to access a small port that is placed under the skin. To control the size of the stoma, the gastric band can be tightened or loosened over time by the physician or another technician extracorporeally by increasing or decreasing the amount of saline solution in the band via the access port to change the size of the passage or stoma.
Providing fine adjustments of the gastric band after initial stoma sizing has proven a significant improvement in the adjustable gastric banding procedure. However, there is an ongoing difficulty in determining when to further adjust the gastric band and how much to increase or decrease the band's size or diameter to achieve a desired stoma size. Numerous gastric bands have been developed to allow a physician or other technician to adjust an implanted gastric band. In general, these band systems include a sensor for measuring or determining parameters associated with the patient and in response, the physician or technician acts to adjust the volume of fluid in the band based on the patient parameters. For example, one adjustable gastric band system determines when the pressure in a patient's stomach exceeds a pre-set limit and provides an alarm to an external control device. A doctor or other operator then responds by loosening the gastric band by removing an amount of fluid from the band via the external access port and fill line. In another gastric band system, components for adjusting the size of the gastric band are implanted within the patient, and when a physical parameter related to the patient, such as stomach pressure or the physical position of the patient, are determined, an external control unit outside the patient's body is operated to power the implanted components to adjust the size of the band, e.g., by adding or removing a preset volume of fluid from the band.
While providing improved control over adjustable gastric bands, the existing gastric bands do not meet the needs of patients. In part, the deficiencies in the existing adjustable gastric bands are due to the need for the patient to be treated by a doctor or other technician to adjust the size of the gastric band and the formed stoma via an external control unit. Other deficiencies are related to the unreliability or inaccuracy of sensing parameters related to the patient and correlating this to a desired stoma size. Further, some of the existing gastric bands require insertion of sensors into the patient, such as into or onto the stomach to determine stomach pressure. Due to these and other limitations of existing technologies, there remains a need for an improved gastric banding system, and associated adjustment methods, for providing improved adjustments to the size of a stoma in a patient being treated for obesity.